Can you list the main categories of design patterns and their examples?

The main categories of design patterns are divided into three groups:

1. Creational — responsible for creating objects while hiding the details of their creation.

   • Examples: Singleton, Factory Method, Abstract Factory, Builder, Prototype.

2. Structural — help organize classes and objects into larger structures.

   • Examples: Adapter, Decorator, Facade, Composite, Proxy.

3. Behavioral — define ways objects interact.

   • Examples: Observer, Strategy, Command, Iterator, State.

For example, Singleton guarantees that a class has only one instance, while Observer allows objects to subscribe to events of another object.